**Tissue Characterization of Carotid Plaques**

Masanori Kawasaki, Shinichi Yoshimura and Kiyofumi Yamada

Additional information is available at the end of the chapter

http://dx.doi.org/10.5772/57155

## **1. Introduction**

Carotid plaque vulnerability has been reported to be associated with stroke and other cerebrovascular events [1, 2]. Therefore, tissue characterization of carotid plaques is important to evaluate the risk of cerebrovascular disease and outcome of treatment for carotid arterial stenosis. Stabilization of vulnerable plaques rather than regression of plaque volume is considered the major contributor to beneficial effects on cerebrovascular events [3].

With respect to the ultrasound technique, ultrasonic tissue characterization of the myocar‐ dium with an integrated backscatter (IBS) analysis was developed, which is capable of providing both conventional two-dimensional echographic (2DE) images and IBS images. In studies of the myocardium, calibrated myocardial IBS was significantly correlated with the volume fraction of interstitial fibrosis [4, 5]. In preliminary *in vitro* studies, IBS values reflected the structural and biochemical composition of atherosclerotic lesion and could differentiate fibrofatty, fatty and calcification of arterial walls [6-8]. However, it is not precise, because IBS values of lipid pool and intimal hyperplasia were similar. Discrimina‐ tion of intimal hyperplasia, fibrous cap and thrombus, and sensitivity and specificity of these measurements were not studied in these papers. Furthermore, extent evaluation of each composition, that is, two-dimensional (2D) tissue structure, in entire plaque has not been examined. Therefore, we measured IBS values in carotid arteries in patients com‐ pared before and immediately after death, and compared these IBS values with their histopathological features. Subsequently, we constructed 2D color-coded maps of arteries with plaque to assess visually the arterial tissue characteristics.

© 2014 Kawasaki et al.; licensee InTech. This is a paper distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
